 If you liked
Mahou Sensei Negima!
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 ...then you might like
Leader's High!
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Both are about a boy that starts working in a school, and both have magic.
In Negima!, the boy is a wizard that starts as a teacher at a normal all-girls school. In Leader's High the boy couldn't care less about magic, but have to take over after his father as principal on a magic school. In both mangas plenty of things get in the way.
Both are good reads (I like Negima! better, though), and you surely would like the other if you liked the one.